Respiratory effects of a balanced anesthetic technique--revisited fifteen years later.

Five hundred and fifty patients underwent general anesthesia with fentanyl, diazepam, and methohexital. Forty-seven (8.5%) developed signs of hypoventilation or airway obstruction. Arterial blood gas analysis revealed mild hypoxemia in three of the 47 cases and mild hypercarbia in six. Airway obstruction was more predictive of abnormal blood gas values than was hypoventilation.